Recording medium, playback apparatus, recording apparatus, playback method, and recording method for reducing processing load during copyright protection at the TS packet level

ABSTRACT

A recording medium enables special playback processing although part of the AV stream recorded therein is transformed. An AV stream, a first EP map, and a second EP map are recorded on the recording medium. In the AV stream, a part of the multiplexed stream including a first video stream and a second video stream is transformed. The first EP map indicates one or more entry points of the first video stream and the second EP map indicates one or more entry points of the second video stream. TS packets constituting I-pictures of the first video stream are indicated by every 4N-th entry point in the first EP map, and TS packets constituting I-pictures of the second video stream are indicated by the entry points whose presentation time is closest to the presentation time of any one of the every 4N-th entry point in the first EP map.

This application claims benefit to the provisional U.S. application Ser.No. 60/996,090, filed Nov. 1, 2007.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to an information recording medium, aplayback method thereof, and a recording method thereof, in particular,to a technology for realizing special playback such asfast-forward/rewind. Here, the information recording medium is a BD-ROMor the like having recorded thereon contents such as video and audio,with copyright protection.

(2) Description of the Related Art

Special playback functions such as fast-forward/rewind are indispensablefunctions for playing back an AV stream recorded on a BD-ROM, DVD, orthe like.

In general, a player can perform special functions such asfast-forward/rewind by executing reading of a disc, decoding of the readdata, and the like at a speed faster than a normal playback speed, andthen playing it back. However, this method places burden on the player,causing the player to be unable to perform processing at the speedrequired for high-speed playback such as 10× for fast-forward/rewind.

Accordingly, in order to realize special playback such asfast-forward/rewind, the player needs to read and decode part of the AVstream while making temporal skips. For example, the player may selectintra-frame encoded images (hereinafter, referred to as “I-pictures”) invideo included in an AV stream in accordance with the speed offast-forward/rewind, and performs reading and decoding. However, an AVstream on a BD-ROM or DVD contains various streams such as video, audio,and subtitles multiplexed into the AV stream. Besides, pictures vary insize in a case where the video is encoded using variable lengthencoding. Accordingly, identifying an I-picture pertaining to a desiredtime requires analysis processing of the AV stream, thereby consuming alarge amount of processing time.

Thus, BD-ROMs use entry maps to realize fast-forward/rewind. An entrymap is composed of a list of multiple entry points each indicating anaccess position in an AV stream. Each entry point is information inwhich a file position within the AV stream corresponds to a playbacktime of data located at the file position. For example, an entry mapincluding entry points each composed of a starting file position of anI-picture included in an AV stream on an information recording mediumand the presentation time of the I-picture allows the playback apparatusto identify the position, of the I-picture, corresponding to theplayback time without analyzing the AV stream, by referring to the entrymap. As a result, the playback apparatus is able to perform partialplayback of the AV stream, thereby realizing efficientfast-forward/rewind without burden. Patent Document 1 discloses a datastructure and a creation method of an entry map for identifyingpositions of I-pictures.

Patent Document 1: Japanese Laid-Open Patent Application Publication No.2000-228656

In manufacturing BD-ROM playback apparatuses which handle HDTV contents,demand for copyright protection at the level of TS packets constitutingthe AV stream is high. However, in order to realize copyright protectionusing such as special encryption and transformation at the TS packetlevel, it is required to perform decryption processing, restorationprocessing or the like in real time at the uppermost stream when readingfrom the BD-ROM. Especially if the AV stream is provided for ahigh-speed special playback such as over 10×, such real time processingwill incur a large burden.

In addition, multiple video streams may be multiplexed into an AV streamin a BD-ROM to realize Picture-in-Picture playback or 3D playback.

If TS packets constituting two video streams in an AV stream aretransformed and the AV stream is provided for a high-speed specialplayback such as 10×, simultaneous restoration of the transformed TSpackets of these multiple video streams need to be realized at 10×. Ifthe BD-ROM playback apparatus is to be designed assuming such aworst-case scenario, it will inevitably require addition of specialhardware, increase in operation clock speed, and the like. This willnecessitate further modification and improvement of the present BD-ROMplayers, which goes against the idea of encouraging broad use of theplayback apparatuses through standardization.

SUMMARY OF THE INVENTION

The present invention was conceived in view of the above problem andaims to provide a recording medium, a recording method, and a playbackapparatus and a playback method for playing back the recording medium,which are able to prevent increase in processing load due to realizationof copyright protection at the TS packet level.

In order to achieve the stated aim, the recording medium of the presentinvention is a recording medium having recorded thereon an AV stream andstream information. Here, the AV stream includes (a) TS packetscomposing a primary video stream and (b) TS packets composing asecondary video stream, the stream information includes: a first entrymap indicating a plurality of associations each associating (a) a startposition of, among the TS packets composing the primary video stream, agroup of TS packets which constitute an entry unit with (b) apresentation time stamp of the group of TS packets; and a second entrymap indicating a plurality of associations each associating (a) a startposition of, among the TS packets composing the secondary video stream,a group of TS packets which constitute an entry unit with (b) apresentation time stamp of the group of TS packets of the secondaryvideo stream, each group of TS packets constituting an entry unit storesan intra-frame encoded image therein, among the TS packets composing theprimary video stream, one or more TS packets have been transformed andTS packets which constitute every N-th entry unit, in an order of thestart position, are untransformed, N being an integer of 2 or more, andeach TS packet which constitutes one of the entry units of the secondaryvideo stream and whose presentation time stamp is in a predeterminedrelationship with a presentation time stamp of the every N-th entryunit, is untransformed.

According to the stated structure, transformation for the purpose ofcopyright protection is not executed on (a) TS packets which constituteone of every N-th entry unit of the primary video stream and (b) TSpackets which constitute an entry unit of the secondary video stream andwhose presentation time stamp attached thereto is in a predeterminedrelationship with the one of every N-th entry unit of the primary videostream. Consequently, selectively using entry units stored in these TSpackets eliminates the need for restoring the transformed TS packetsconstituting the primary video stream and TS packets constituting thesecondary video stream. As a result, increase in processing load duringhigh-speed fast-forward/rewind playback can be prevented, therebyrealizing the copyright protection using transformation of the TSpackets within a permissible range of the processing capability of astandard-model BD-ROM player, without adding special hardware orincreasing operation clock speed.

Accordingly, copyright protection is realized by transforming part ofthe AV stream and recording the post-transformation AV stream, and atthe same time, high-speed and simultaneous fast-forward/rewind of theprimary video stream and secondary video stream can be performed.

Here, among the TS packets of the secondary video stream, TS packetsconstituting the entry units closest to every N-th entry unit of theprimary video stream are chosen to be untransformed, thereby realizingfast-forward/rewind of the primary video stream and secondary videostream in an as closely synchronized manner as possible.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, advantages and features of the invention willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings which illustrate a specificembodiment of the invention. In the drawing:

FIG. 1 shows a use form of a recording medium of the present invention;

FIG. 2 shows an internal structure of a BD-ROM;

FIG. 3 shows an internal structure of IndexFile;

FIG. 4 shows an internal structure of a Movie Object file;

FIG. 5 shows a structure of an AV stream;

FIG. 6 shows an example of Picture in Picture;

FIG. 7 schematically shows how streams are multiplexed into an AVstream;

FIG. 8 shows further details on how a video stream and an audio streamare stored into a PES packet string;

FIG. 9 shows a structure of a TS packet and a source packet in an AVstream;

FIG. 10 shows a data structure of PMT;

FIG. 11 shows an internal structure of a stream information file;

FIG. 12 shows an internal structure of stream attribute information;

FIG. 13 shows an internal structure of an entry map;

FIG. 14 shows an internal structure of a PlayList;

FIG. 15 shows an internal structure of a PlayItem;

FIG. 16 shows relationship between restoration segments and restorationparameters with respect to an AV stream;

FIG. 17 shows a function of restoration byte code data;

FIG. 18 shows a structure of a restoration entry with respect totransformed data in an AV stream and how the restoration entry, as arestoration descriptor, is stored into the AV stream;

FIG. 19 shows untransformable ranges which are not allowed to betransformed, in a video stream included in an AV stream;

FIG. 20 shows video frame strings in video streams included in an AVstream;

FIG. 21 shows PTS positions of entry points of a primary video and asecondary video with respect to STC which is a playback time axis of theAV stream, and entry points indicating untransformable I-pictures in theentry map of the secondary video;

FIG. 22 shows relationship between untransformable TS packets of theprimary video stream and secondary video stream, using framesconstituting each video stream;

FIG. 23 shows SPN positions of the entry points of the primary video andsecondary video with respect to file position of the AV stream, andentry points indicating untransformable I-pictures in the entry map ofthe secondary video in a first modification;

FIG. 24 shows SPN positions of entry points of the primary video withrespect to the file position of the AV stream, and untransformableI-pictures of the secondary video in a second modification;

FIG. 25 shows the PTS positions of the entry points of the primary videoand the secondary video with respect to STC which is the playback timeaxis of the AV stream, and entry points indicating untransformableI-pictures in the entry map of the secondary video in a thirdmodification;

FIG. 26 shows the SPN positions of the entry points of the primary videoand secondary video with respect to the file position of the AV stream,and entry points indicating untransformable I-pictures in the entry mapof the secondary video in a fourth modification;

FIG. 27 shows the PTS positions of the entry points indicatinguntransformable I-pictures, in a fifth modification, with respect to STCwhich is the playback time axis of the AV stream;

FIG. 28 shows the PTS position of the entry points indicatinguntransformable I-pictures, in a sixth modification, with respect to STCwhich is the playback time axis of the AV stream;

FIG. 29 shows the PTS positions of the entry points indicatinguntransformable I-pictures, in a seventh modification, with respect toSTC which is the playback time axis of the AV stream;

FIG. 30 shows the PTS positions of the entry points indicatinguntransformable I-pictures, in an eighth modification, with respect toSTC which is the playback time axis of the AV stream;

FIG. 31 shows an inner structure of a playback apparatus;

FIG. 32 shows an inner structure of a system target decoder;

FIG. 33 is a flowchart showing processing by a data analysis executionunit 17;

FIG. 34 is a flowchart showing processing steps of playback entry pointselection processing;

FIG. 35 shows an inner structure of a recording apparatus;

FIG. 36 shows a flowchart of a recording method;

FIG. 37 is a flowchart showing processing steps of untransformablepacket specification processing; and

FIG. 38 shows a structure of a restoration entry with respect totransformed data in an AV stream in a modification, and how therestoration entry, as a restoration entry packet, is stored into the AVstream.

DETAILED DESCRIPTION OF THE INVENTION First Embodiment

The following describes a first embodiment of a recording medium of thepresent invention. First, among various aspects of the recording mediumof the present invention, a use form is described. FIG. 1 shows the useform of the recording medium of the present invention. In FIG. 1, therecording medium of the present invention is a BD-ROM 100 which is usedto supply a motion picture to a home theater system further composed ofa playback apparatus 200, a remote controller 300, and a television 400.

The BD-ROM 100 is a recording medium having recorded thereon a motionpicture.

The playback apparatus 200 is an Internet-compliant digital homeappliance, and is capable of playing back the BD-ROM 100. The playbackapparatus 200 downloads content from a server of a film distributor viaa network and stores the downloaded content into a local storagethereof. This way, the playback apparatus 200 is able to expand/updatethe content of the BD-ROM 100 by combining the content stored in thelocal storage and the content recorded on the BD-ROM 100. The technologywhich handles data not recorded on the BD-ROM 100 as if the data isrecorded on the BD-ROM 100, by combining the content of the BD-ROM 100and the content of the local storage, is called “virtual package”.

Described above is the use form of the recording medium of the presentinvention.

Next, description is given on a production form of the recording mediumof the present invention. The recording medium of the present inventioncan be realized by modifying a file system.

<Outline of BD-ROM>

FIG. 2 shows a structure of the BD-ROM. The fourth row in the figureshows the BD-ROM 100, while the third row shows a track on the BD-ROM.In the figure, the track is stretched out horizontally, although inreality it spirals from the inner periphery to the outer periphery ofthe BD-ROM 100. The BD-ROM 100, like other optical discs such as DVDsand CDs, has a recording area formed spirally from the inner peripheryto the outer periphery therein, and has, between the lead-in of theinner periphery and the lead-out of the outer periphery, a logicaladdress space capable of recording logical data. Additionally, insidethe lead-in, there is a special area called BCA (Burst Cutting Area)which can be read only by drives. Being unreadable by applications, thisarea is often used for copyright protection technology.

In the logical address space, volume information of a file system isrecorded from the beginning thereof, and subsequently, application datasuch as video data is recorded. The file system is a structure whichrepresents data on a disc in units of directories or files, and in theBD-ROM 100, UDF (UniversalDisc Format) is used. PCs (Personal Computers)for everyday use also use a file system called FAT or NTFS and present,on computer, data stored in a hard disc in a structure of directoriesand files, thereby increasing usability. The use of file system enablesthe ED-ROM 100 to read logical data, which is stored in the same manneras in a general purpose PC, using the directory and file structure.

With use of the directory and file structure, the application layerformat (application format) of the BD-ROM 100 is presented as the firstrow of the figure. According to the directory and file structure of theBD-ROM 100, there is a BDMV directory directly under the root directory(ROOT). The BDMV directory records data processed by the BD-ROM 100,such as AV contents and management information. Under the BDMVdirectory, there are IndexFile (index.bdmv), a Movie Object file(MovieObject.bdmv), a PLAYLIST directory, a CLIPINF directory, and aSTREAM directory. The IndexFile defines an IndexTable constitutingTitles, and the Movie Object file defines a dynamic scenario. The STREAMdirectory, CLIPINF directory, and PLAYLIST directory include AV streams(XXX.M2TS) storing AV contents such as video and audio which aremultiplexed, stream information files (XXX.CLPI) storing managementinformation of the AV streams, and PlayList files (YYY.MPLS) defininglogical playback paths of the AV streams, respectively.

Directly under the root directory (ROOT), there is also a BDPLSdirectory which records restoration byte code data (ZZZ.BDP). In aBD-ROM including the BDPLS directory, an AV stream is partiallytransformed at the TS packet level in advance. The restoration byte codedata is an execution program, and when executed, generates restorationparameters to restore the transformed AV stream. Prior to playing backthe AV stream, the playback apparatus generates restoration parametersby executing the restoration byte code data, restores the transformed AVstream using the generated restoration parameters, and plays back therestored AV stream.

It should be noted that these directory names and file names are definedfor the purpose of explaining the present embodiment, and accordingly,different names can be applied when put to practical use.

In the following, description is given on the data structure of eachfile under the BDMV directory.

<Structure of BD-ROM (1) IndexFile>

First, the IndexFile (Index.bdmv) is described. The IndexFile includesIndexTable shown in FIG. 3. The IndexTable is a table of the highestlayer and defines the title structure of all the Titles, TopMenu,FirstPlay and the like stored in the BD-ROM. This table specifies MovieObjects included in the Movie Object file which are first executed byall the Titles, TopMenu, and FirstPlay. Each time a Title or a Menu isinvoked, the playback apparatus of the ED-ROM refers to the IndexTableand executes a predetermined Movie Object. Here, the FirstPlay is set bya content provider and has been set to a Movie Object that isautomatically executed when the disc is inserted. The TopMenu specifiesa Movie Object invoked when a command such as “return to menu” isexecuted by user operation of the remote controller.

<Structure of BD-ROM (2) Movie Object File>

Next, the Movie Object file (MovieObject.bdmv) is described.

As shown in FIG. 4, multiple Movie Objects are defined in the MovieObject file, and each Movie Object is identified by a Movie Object ID.Each Movie Object includes one or more navigation commands instructing aplayback of a PlayList, transition to another Movie Object or Title, andthe like, and the playback apparatus sequentially executes the string ofnavigation commands. For example, when “PlayPL#N” is described, theplayback apparatus selects a file name of a PlayList corresponding to“PlayPL#N” from the PlayList directory and plays back the selectedPlayList. Also, for example, when “JumpObject#N” is described, theplayback apparatus selects the corresponding Movie Object from the MovieObject file and executes the selected Movie Object.

Next, the AV stream file (XXX.M2TS) and stream information file(XXX.CLPI) are described.

<Structure of BD-ROM (3) AV Stream>

The AV stream is a digital stream of MPEG-2 transport stream format.

FIG. 5 shows a structure of the AV stream. As shown in FIG. 5, the AVstream is obtained by multiplexing one or more among video streams,audio streams, presentation graphics streams, and interactive graphicsstreams. The video stream indicates a primary video or a secondary videoof a motion picture, the audio stream indicates audio part of a motionpicture, and the presentation graphics stream indicates subtitles of amotion picture. Here, when the AV stream stores Picture-in-Picturevideo, as shown in FIG. 6, the primary video constitutes ordinary videodisplayed in a screen, while the secondary video constitutes a smallscreen within the primary video. If the AV stream is ofthree-dimensional images, the primary video is for right-eye image, andthe secondary video is for left-eye image. The interactive graphicsstream indicates a dialogue screen created by placing GUI parts on ascreen. Each stream included in the AV stream is identified by PID. Forexample, a video stream used for the primary video of a motion pictureis allocated 0x1011, an audio stream is allocated 0x1100 to 0x111F, apresentation graphics stream is allocated 0x1200 to 0x121F, aninteractive graphics stream is allocated 0x1400 to 0x141F, and a videostream used for the secondary video of a motion picture is allocated0x1B00 to 0x1B1F.

FIG. 7 is a schematic diagram showing how the AV stream is multiplexed.First, a video stream 701 composed of multiple video frames, and anaudio stream 704 composed of multiple audio frames are converted to PESpacket strings 702 and 705, respectively, and further converted to TSpackets 703 and 706, respectively. Similarly, data of a presentationgraphics stream 707 and of an interactive graphics 710 are converted toPES packet strings 708 and 711, respectively, and further converted toTS packets 709 and 712, respectively. An AV stream 713 is formed bymultiplexing these TS packets into one stream.

FIG. 8 gives further details on how a video stream is stored into an PESpacket string. The first row of the figure indicates the video framestring of the video stream. The second row indicates the PES packetstring. As shown by arrows yy1, yy2, yy3, and yy4 in the figure,I-pictures, B-pictures, and P-pictures which are multiple VideoPresentation Units in the video stream are divided into units ofpictures and stored into payloads of PES packets separately. Each PESpacket has a PES header storing therein PTS (Presentation Time-Stamp)which is a presentation time of the picture, DTS (Decoding Time-Stamp)which is a decoding time of the picture, and the like.

FIG. 9 shows the final format used for TS packets to be written into anAV stream. Each TS packet is a fixed-length packet composed of a 4-byteTS header and a 184-byte TS payload. The TS header includes informationsuch as PID identifying a stream, and the TS payload stores data. EachPES packet is divided and stored into TS payloads. In a BD-ROM, each TSpacket has a 4-byte TP_Extra_Header attached thereto and accordingly, iswritten into an AV stream as a 192-byte source packet. TheTP_Extra_Header includes information such as ATS (Arrival_Time_Stamp).ATS shows the transfer starting time of the TS packet to a PID filter.Source packets are arranged in the AV stream as shown in the lower levelof FIG. 8, and the number which is incremented from the beginning of theAV stream is called SPN (Source Packet Number).

Furthermore, in addition to the streams for video, audio, subtitles, andthe like, TS packets in an AV stream include PAT (Program AssociationTable), PMT (Program Map Table), PCR (Program Clock Reference) and thelike. PAT indicates the PID of the PMT used in the AV stream, and thePID of the PAT itself is registered as “0”. PMT includes (i) PIDs ofstreams such as for video, audio, subtitles and others, (ii) attributeinformation corresponding to each PID, and (iii) descriptors related tothe AV stream. The descriptors include such as copy control informationwhich instructs copying of the AV stream to be permitted or rejected. Inorder to synchronize ATC (Arrival Time Clock) which is the time-axis ofATS, with STC (System Time Clock) which is the time-axis of PTS and DTS,PCR has information on STC time corresponding to ATS at which the PCRpacket is transferred to a decoder.

FIG. 10 shows details of the data structure of PMT. At the beginning ofPMT, a PMT header describing the length of data included in PMT isarranged. Subsequent to that, multiple descriptors regarding the AVstream are arranged. The descriptors describe such as theabove-mentioned copy control information. In addition, with respect tothe AV stream of the present embodiment, transformation is performed atthe TS packet level using a transformation method described later, and arestoration descriptor used for restoring the transformation isdescribed as a descriptor of PMT.

After the descriptors, multiple pieces of stream information regardingthe streams included in the AV stream are arranged. Each piece of streaminformation includes a stream type for identifying compression codec orthe like of the stream, PID of the stream, and stream descriptorsdescribing attribute information of the stream (frame rate, aspectratio, etc.). The number of the stream descriptors is equivalent to thenumber of the streams included in the AV stream.

<Structure of BD-ROM (4) Stream Information File>

Next, description is given on the stream information file.

The stream information file, which is management information of an AVstream, as shown in FIG. 11, corresponds one-to-one with an AV stream,and includes stream attribute information and entry maps.

The stream attribute information, as shown in FIG. 12, includes piecesof attribute information which correspond one-to-one to the streamsincluded in the AV stream and which are registered for each PID. Thevideo stream, audio stream, presentation graphics stream, andinteractive graphics stream each have its own attribute information. Thevideo stream attribute information includes information on what kind ofcompression codec is used to compress the video stream, what theresolution of each picture data constituting the video stream is, whatthe aspect ratio is, what the frame rate is, and the like. The audiostream attribute information includes information on what kind ofcompression codec is used to compress the audio stream, how manychannels the audio stream has, to which languages the audio streamcorresponds, how many sampling frequencies there are, and the like.These information are used for initialization of the decoder and thelike before the playback apparatus performs a playback.

The entry map, as shown in FIG. 13, is table information which describesPTS indicating presentation time of each intra-frame encoded image(hereinafter, referred to as “I-picture”) in a video stream included inthe AV stream, and SPN of the AV stream at which each I-picture starts.

In the present embodiment, information composed of a set of PTS and SPNindicated in one row of the table is called “entry point”, and a groupof TS packets storing an I-picture indicated by an entry point is called“entry unit”. In addition, a value which starts with “0” and isincremented by one at each entry point is called “entry point ID”(hereinafter, referred to as “EP_ID”). By using this entry map, theplayback apparatus is able to specify, in the AV stream, file positionswhich correspond one-to-one with arbitrary positions on the time-axis ofthe video stream. For example, when performing special playback such asfast-forward/rewind, the playback apparatus is able to performprocessing efficiently without analyzing the AV stream by specifyingI-pictures registered in the entry map and selectively playing back thespecified I-pictures. The entry map is created for each video streammultiplexed into the AV stream, and is managed by PID.

<Structure of BD-ROM (5) PlayList File>

Next, the PlayList file (YYY.MPLS) is described.

A PlayList indicates a playback path of an AV stream. As shown in FIG.14, a PlayList includes one or more PlayItems 501, and each PlayItemindicates a playback section with respect to the AV stream. EachPlayItem 501 is identified by a PlayItem ID and is described in order ofplayback within the PlayList. The PlayList includes entry marks 502 eachindicates a playback start point. Each entry mark 502 can be assigned ina playback section defined by a PlayItem, and as shown in FIG. 14, isassigned to a position which can be a playback start point with respectto the PlayItem and is used for a playback from a specified time. Forexample, a motion picture Title can be played back in units of chaptersby assigning the entry marks 502 to positions where chapters start.

Content of a PlayItem is described with reference to FIG. 15. ThePlayItem includes information on stream information to be referred to601, a playback start time 602, a playback end time 603, and a streamselection table 605. Since the playback start time and playback end timeare time information, the playback apparatus performs playbackprocessing after (a) obtaining SPN corresponding to the specifiedplayback start time and SPN corresponding to the specified playback endtime by referring to the entry map of the stream information file and(b) specifying the read start position.

The stream selection table 605 is a table indicating whether each streammultiplexed into the AV stream to be referred to is valid or invalidwhen playing the PlayItem. Specifically, according to the example shownin FIG. 15, the AV stream includes one video stream, three audiostreams, four presentation graphics streams, and three interactivegraphics streams. According to the stream selection table 605, amongthese streams, video, audio 1, audio 2, presentation graphics 1,presentation graphics 2, and interactive graphics 1 are valid.Accordingly, in this PlayItem, the above-mentioned valid elementarystreams are playable, while the other elementary streams are not allowedto play. The stream selection table 605 also stores attributeinformation of each stream. Here, the attribute information isinformation indicating characteristics of each stream. For example,audio, presentation graphics, and interactive graphics include languageattribute and the like.

<Structure of BD-ROM (6) Restoration Byte Code Data>

Next, description is given on restoration byte code data under the BDPLSdirectory, and the transformation method and data structure, of the AVstream, required to implement copyright protection using the restorationbyte code data.

Described below are the transformation method and data structure of theAV stream.

First, the restoration segment and restoration parameter are described.As shown in FIG. 16, the AV stream is divided into multiple restorationsegments based on the entry map. Every 25 entry points from thebeginning, the AV stream is divided to a restoration segment. However,it should be noted that the final restoration segment includes between25 to 49 entry points so as not to be of less than 25 entry points. Arestoration segment ID (SG_ID) starts from “0” at the beginning of therestoration segment, and is incremented by one. A restoration parameterwhich is a byte string having a constant length is defined for eachrestoration segment. When transformed data in the AV stream is to berestored, the restoration parameter defined by the restoration segmentto which the transformed data belongs is used.

Next, the restoration byte code data is described with reference to FIG.17. The restoration byte code data is a program code executable by avirtual operation means such as JAVA, and, when executed given thenumber of the AV stream and restoration segment ID, generates arestoration parameter corresponding thereto. The restoration byte codedata can be arbitrarily created by a content provider. Accordingly, forexample, the content provider is requested to make efforts such as, withuse of a key on the BD-ROM disc or in the playback apparatus, allowingonly the playback apparatus having the correct key to generate therestoration parameter, thereby preventing an illegal playback apparatusfrom performing playback, or obfuscating program codes to prevent theprogram itself from being illegally analyzed.

<Details of Transformation Method of AV Streams>

The transformation method of an AV stream is described in detail in thefollowing.

FIG. 18 shows how an AV stream is transformed. The AV stream istransformed by steps of selecting pre-transformation data, creating arestoration entry, recording a restoration descriptor into PMT, andoverwriting the pre-transformation data with post-transformation data.

The pre-transformation data indicates original data before part of avideo stream, audio stream and the like which are multiplexed into theAV stream is transformed. The pre-transformation data which is of aconstant length can be selected at an arbitrary position in the payloadof a TS packet. Further, in the present embodiment, some of the TSpackets are protected as untransformable packets, and thepre-transformation data cannot be selected from the untransformablepackets.

The restoration entry is created using the pre-transformation data. Therestoration entry includes the following fields: a transformationinstruction flag, a relative packet count, an intra-packet position, andan overwrite value. The overwrite value is set to the pre-transformationdata. The intra-packet position describes a byte offset from thebeginning of the source packet V including the pre-transformation data.The relative packet count contains the number of packets from the sourcepacket V of PMT which exists prior to the pre-transformation data to thesource packet including the pre-transformation data. The transformationinstruction flag contains at least either “restoration not required” or“restoration required”. When transformation processing has beenperformed with respect to data included in the AV stream, “restorationrequired” is contained. For each restoration entry which is created asmentioned above, a mask restoration entry is created by performing anXOR operation on the restoration entry and the restoration parametercorresponding to the restoration segment including thepre-transformation data. It should be noted that while masking isperformed by an XOR operation here, other invertible logical operationsor encryption processing can be used instead.

The mask restoration entry is included in a restoration descriptor whichis recorded in PMT as the descriptor thereof. Here, the restorationdescriptor is registered as the first descriptor of PMT so as to enablethe playback apparatus to perform analysis processing of PMTefficiently.

Finally, the position of the pre-transformation data in the AV stream isoverwritten by the post-transformation data such as a random value.

Even in a case where the transformation processing has not beenperformed in one or more of the restoration segments of the data of theAV stream, a restoration entry is created with the transformationinstruction flag set to “restoration not required”, and a restorationdescriptor is created by masking the created restoration entry with therestoration parameter and is recorded in PMT. It should be noted thatwhile a piece of pre-transformation data is stored in one restorationentry here, multiple pieces of pre-transformation data can be stored inone restoration entry. With this structure, the number of PMT can bereduced with respect to the pre-transformation data.

<Untransformable Ranges in Primary Video Stream>

Next, description is given on untransformable ranges in a video streamincluded in the AV stream, in which the TS packets are not allowed to betransformed. First, description is given with respect to the primaryvideo stream.

FIG. 19 shows, in a primary video stream included in the AV stream, theuntransformable ranges not allowed to be transformed. The first row ofFIG. 19 indicates the data structure of the pictures in the primaryvideo stream, and the second row of FIG. 19 indicates the TS packetsstoring the AV stream. Arrows indicate positions of the source packetscontaining the beginning of the pictures (shaded areas in the secondrow). The third row of FIG. 19 indicates an entry map corresponding tothe primary video stream, and each entry point indicates the firstpacket among the TS packets storing an I-picture. Here, each I-pictureindicated by an entry point whose EP_ID is a multiple of four isrendered untransformable, and each entry unit, in the AV stream,composed of the TS packets storing the I-picture becomes anuntransformable range. The example in FIG. 19 shows that the I-picturesindicated by the first entry point (EP_ID=0) and the fourth entry point(EP_ID=4) counting from the first entry point are untransformable. If,for example, the AV stream in FIG. 19 further continues, the I-picturesindicated by the entry points such as EP_ID=8, EP_ID=12, EP_ID=16 . . .are untransformable. Here, the I-pictures indicated by the entry pointswhose EP_ID is a multiple of four are untransformable.

Thus, by cyclically rendering part of the TS packets untransformable soas to ensure that the part is not transformed, the playback apparatuswhich plays back the recording medium of the present embodiment is ableto specify I-pictures which are not transformed, in a video stream inthe entry map. Consequently, the playback apparatus can perform, byselecting and playing the untransformed I-pictures, special playbacksuch as fast-forward/rewind without executing restoration processingwhich causes a load on the apparatus playback.

<Untransformable Ranges in Secondary Video Stream>

Next, description is given on untransformable ranges in the secondaryvideo stream.

FIG. 20 shows video frame strings of video streams included in the AVstream. The upper row of FIG. 20 shows a video frame string of a videostream which is a primary video and has PID of 0x1011, while the lowerrow of FIG. 20 shows a video frame string of a video stream which is thesecondary video and has PID of 0x1B00. As shown in FIG. 20, intervalsbetween an I-picture and the next I-picture may differ between theprimary video and the secondary video. Here, if it is assumed thatI-pictures indicated by the entry points whose EP_ID is a multiple offour are untransformable for the entry maps of both the primary videoand secondary video, then when the playback apparatus plays back theI-pictures indicated by the entry points whose EP_ID is a multiple offour, for both the primary video and secondary video, while performingspecial playback such as fast-forward/rewind, it may result in playingpictures whose PTSs are considerably distant between the primary videoand the secondary video in terms of time.

Thus, entry points indicating untransformable I-pictures in the entrymap of the secondary video are determined as shown in FIG. 21. FIG. 21shows PTS positions of entry points with respect to STC which is aplayback time axis of the AV stream. Arrows shown in the second row ofFIG. 21 indicate PTS positions of entry points of the primary videohaving PID of 0x1011. EP_ID of each of these entry points is a multipleof four, and the I-pictures indicated by these entry points areuntransformable. Arrows shown in the third row of FIG. 21 indicate PTSpositions of entry points of the secondary video having PID of 0x1B00.Here, with respect to each PTS position of an entry point whose PID is0x1011 and EP_ID is a multiple of four, an I-picture indicated by, amongthe entry points having PID of 0x1B00, an entry point whose PTS isclosest to the PTS position is rendered untransformable, and the entryunit storing this I-picture in the secondary stream is rendereduntransformable. For example, among the entry points having PID of0x1B00, an entry point having EP_ID of B is closest to the PTS of theentry point whose PID is 0x1011 and EP_ID is 4N. Accordingly, theI-picture indicated by this entry point is rendered untransformable.Similarly, among the entry points having PID of 0x1B00, the entry pointhaving EP_ID of C is closest to the PTS of the entry point whose PID is0x1011 and EP_ID is 4(N+1). Accordingly, the I-picture indicated by thisentry point is rendered untransformable. Furthermore, among the entrypoints having PID of 0x1B00, the entry point having EP_ID of E and theentry point having EP_ID of F are closest to the PTS of the entry pointwhose PID 0x1011 and EP_ID is 4(N+2). In this case, both I-picturesindicated by these two entry points are rendered untransformable.

The I-pictures rendered untransformable are shaded pictures in thepicture strings in the video streams shown in FIG. 22. With the AVstream having this data structure, when performing fast-forward/rewindof the primary and secondary videos, the playback apparatus can playI-pictures which are closest to each other in terms of presentationtime, using the I-pictures rendered untransformable. This realizes thesynchronized playback of the primary and secondary videos as a result.Here, if the AV stream recorded on the BD-ROM 100 is ofthree-dimensional images, where the primary video is for right-eye imageand the secondary video is for left-eye image, the shaded I-pictures inthe right-eye and left-eye images are closest to each other in terms ofpresentation time, that is to say, the right-eye and left-eye picturesconstituting a three-dimensional frame. This enables naturalthree-dimensional playback when performing fast-forward/rewind playbackusing only these I-pictures.

It should be noted that in FIG. 21, a modification can be made such thatwhen the difference between PTS of an entry point of the primary videowhose PID is 0x1011 and EP_ID is a multiple of four, and PTS of an entrypoint of the secondary video whose PID is 0x1B00 and which is closest tothe aforementioned PTS is more than half of the maximum value of theinterval of I-pictures set by the BD-ROM format, the I-picture indicatedby the entry point having PID of 0x1B00 does not need to be rendereduntransformable. As a result, when playing back an I-picture of an entrypoint whose PID is 0x1011 and EP_ID is a multiple of four, the playbackapparatus is not required to play back a part unnecessarily further awayto play back an untransformable I-picture of an entry point having PIDof 0x1B00. This reduces the load on the playback apparatus.

Also, a modification can be made as in the following: in a case wherethere are two entry points, among the entry points of the secondaryvideo having PID of 0x1B00, whose PTSs are equally closest to the PTS ofan entry point of the primary video whose PID is 0x1011 and EP_ID is amultiple of four, the I-picture indicated by one of the two entry pointswith PTS which is positioned posterior to the other is rendereduntransformable, and the I-picture indicated by the other which ispositioned anterior is not rendered untransformable. For example, inFIG. 21, among the entry points having PID of 0x1B00, the entry pointhaving EP_ID of E and the entry point having EP_ID of F are closest tothe PTS of the entry point whose PID is 0x1011 and EP_ID is 4(N+2). Inaccordance with the modification, only the I-picture indicated by theposteriorly positioned entry point having EP_ID of F is rendereduntransformable.

Up to this point, the data structure of the BD-ROM which is therecording medium of the present invention has been described.

<Conclusion>

As described above, according to the present invention, the followingtwo aspects can be achieved: (i) copyright protection at the TS packetslevel is realized by transforming part of the AV stream; and (ii)because every fourth entry unit in the primary video stream and entryunits, in the secondary video stream, each storing Presentation TimeStamp (PTS) closest to the every fourth entry unit in the primary videostream are ensured to be untransformed, by selectively using theseuntransformed entry units, it is not necessary to execute transformrestoration processing when performing high-speed fast-forward/rewindplayback, thereby preventing increase of processing load.

Here, in particular, the TS packets in the secondary video stream whichare ensured to be untransformed constitute entry units closest, in termsof time, to the every fourth entry unit in the primary video stream.Accordingly, even selective use of the entry units constituted by theseuntransformed TS packets also enables fast-forward/rewind where theprimary video stream and the secondary video stream are as closelysynchronized as possible.

<Modifications>

The following describes modifications of the present embodiment, withrespect to the selection of the I-pictures to be rendereduntransformable in the secondary video.

(1) It should be noted that the untransformable I-pictures in thesecondary video may be determined as shown in FIG. 23. FIG. 23 shows SPNpositions of entry points with respect to the AV stream file. Arrowsshown in the second row of FIG. 23 indicate SPN positions of the entrypoints having PID of 0x1011. EP_ID of each of these entry points is amultiple of four, and the I-pictures indicated by these entry points areuntransformable. Arrows shown in the third row of FIG. 23 indicate SPNpositions of the entry points having PID of 0x1B00. Here, with respectto each SPN position of an entry point with EP_ID of a multiple of four,in the primary video stream having PID of 0x1011, an I-picture indicatedby, among the entry points of the secondary video stream having PID of0x1B00, an entry point whose SPN is closest to the SPN position isrendered untransformable.

For example, among the entry points having PID of 0x1B00, an entry pointhaving EP_ID of B is closest to the SPN of the entry point whose PID is0x1011 and EP_ID is 4N. Accordingly, the I-picture indicated by thisentry point is rendered untransformable. Similarly, among the entrypoints having PID of 0x1B00, the entry point having EP_ID of C isclosest to the SPN of the entry point whose PID is 0x1011 and EP_ID is4(N+1). Accordingly, the I-picture indicated by this entry point isrendered untransformable. Furthermore, among the entry points whose PIDis 0x1B00, the entry point having EP_ID of E and the entry point havingEP_ID of F are closest to the SPN of the entry point whose PID is 0x1011and EP_ID is 4(N+2). In this case, both I-pictures indicated by thesetwo entry points are rendered untransformable.

In the present modification, untransformable I-pictures of the primaryand secondary videos are stored at positions close to each other in thepacket sequences of the AV stream. With the AV stream having this datastructure, when performing fast-forward/rewind of the primary andsecondary videos, the playback apparatus uses I-pictures which are closeto each other in terms of storage position in the file for playback,thereby reducing the load of BD-ROM drive reading processing.

It should be noted that in FIG. 23, a modification can be made such thatwhen the difference between (a) SPN of an entry point having EP_ID of amultiple of four, of the primary video stream having PID of 0x1011, and(b) SPN of, among entry points of the secondary video whose PID is0x1B00, an entry point whose SPN is closest to the SPN pertaining to PIDof 0x1011 is more than a size determined by (half of the maximumtemporal interval between I-pictures set by the BD-ROM format)*(bitratesize of the AV stream), the I-picture pertaining to PID of 0x1B00 doesnot need to be rendered untransformable. As a result, when playing anI-picture of the entry point having EP_ID of a multiple of four, of theprimary video stream having PID of 0x1011, the playback apparatus is notrequired to play back a part unnecessarily further away to play back anuntransformable I-picture of an entry point of the secondary videohaving PID of 0x1B00, thereby reducing the load on the playbackapparatus.

(2) As another modification, the untransformable I-pictures in thesecondary video may be determined as shown in FIG. 24. FIG. 24 shows SPNpositions of entry points with respect to the AV stream file. Arrowsshown in the second row of FIG. 24 indicate SPN positions of the entrypoints having PID of 0x1011. EP_ID of each of these entry points is amultiple of four, and the I-pictures indicated by these entry points areuntransformable. Arrows shown in the third row of FIG. 24 indicate SPNpositions where beginnings of the I-pictures of the secondary videohaving PID of 0x1B00 exist. Here, the first I-picture among I-picturesof the secondary video positioned posterior to the entry point havingEP_ID of a multiple of four, of the primary video having PID of 0x1011,are rendered untransformable. In other words, in the secondary video, anentry unit storing the first I-picture, among the I-pictures whose SPNare positioned posterior to the entry point, of the primary video,having EP_ID of a multiple of four, becomes a untransformable range.

For example, in FIG. 24, among the I-pictures whose PID is 0x1B00 andwhich are positioned posterior to the SPN indicated by the entry pointwhose PID is 0x1011 and EP_ID is 4N, the I-picture#B is the beginning ofthe picture closest to the SPN pertaining to PID of 0x1011. Accordingly,this I-picture is rendered untransformable. Similarly, among theI-pictures positioned posterior to the SPN of the entry point whose PIDis 0x1011 and whose EP_ID is 4(N+1), the I-picture#E is the beginning ofthe picture closest to the SPN of the entry point whose PID is 0x1011and EP_ID is 4(N+1). Accordingly, this I-picture is rendereduntransformable. With this structure, untransformed I-pictures of thesecondary video can be specified using only the entry map of the primaryvideo, thereby reducing the load of implementation of the playbackapparatus.

It should be noted that this can be modified such that when thedifference between SPN of an entry point whose PID is 0x1011 and EP_IDis a multiple of four, and SPN of, among each beginning of pictureswhose PID is 0x1B00 and SPN is positioned posterior to the SPNpertaining to PID of 0x1011, the beginning of a picture whose SPN isclosest to the SPN pertaining to PID of 0x1011 is more than a sizedetermined by (the maximum temporal interval between I-pictures set bythe BD-ROM format)*(bitrate size of the AV stream), the I-picturepertaining to PID of 0x1B00 does not need to be rendereduntransformable. As a result, when playing an I-picture of an entrypoint whose PID is 0x1011 and EP_ID is a multiple of four, the playbackapparatus is not required to play back a part unnecessarily further awayto play back an untransformable I-picture of an entry point having PIDof 0x1B00, thereby reducing the load on the playback apparatus.

(3) As another modification, the untransformable I-pictures in thesecondary video may be determined as shown in FIG. 25. FIG. 25 shows PTSpositions of entry points with respect to the STC which is the playbacktime axis of the AV stream. Arrows shown in the second row of FIG. 25indicate the PTS positions of the entry points having PID of 0x1011.EP_ID of each of these entry points is a multiple of four, and theI-pictures indicated by these entry points are untransformable. Arrowsshown in the third row of FIG. 25 indicate the PTS positions of theentry points having PID of 0x1B00. Here, with respect to each PTSposition whose PID is 0x1011 and EP_ID is a multiple of four, anI-picture indicated by, among the entry points whose PID is 0x1B00 andwhich are positioned posterior to the PTS position, an entry point whosePTS is closest to the PTS position is rendered untransformable.

For example, among the entry points whose PID is 0x1B00 and which arepositioned posterior to the PTS of the entry point whose PID is 0x1011and EP_ID is 4N, the entry point having EP_ID of B is closest to the PTSof the entry point whose PID is 0x1011 and EP_ID is 4N. Accordingly, theI-picture indicated by this entry point is rendered untransformable.Similarly, among the entry points whose PID is 0x1B00 and which arepositioned posterior to the PTS of the entry point whose PID is 0x1011and EP_ID is 4(N+1), the entry point having EP_ID of C is closest to thePTS of the entry point whose PID is 0x1011 and EP_ID is 4(N+1).Accordingly, the I-picture indicated by this entry point is rendereduntransformable. With this data structure, when performingfast-forward/rewind of primary and secondary videos, the playbackapparatus can easily search I-pictures which are close to each other interms of presentation time, thereby realizing efficientfast-forward/rewind of the primary and secondary videos by the playbackapparatus as a result.

It should be noted that this can be modified such that when thedifference between PTS of an entry point whose PID is 0x1011 and EP_IDis a multiple of four, and PTS of an entry point whose PID is 0x1B00 andwhich is closest to the aforementioned PTS is more than the maximumvalue of the interval of I-pictures set by the format, the I-pictureindicated by the entry point having PID of 0x1B00 does not need to berendered untransformable. As a result, when playing back an I-picture ofan entry point whose PID is 0x1011 and EP_ID is a multiple of four, theplayback apparatus is not required to play back a part unnecessarilyfurther away to playback an untransformable I-picture of an entry pointhaving PID of 0x1B00. This reduces the load on the playback apparatus.

(4) As another modification, the untransformable I-pictures in thesecondary video may be determined as shown in FIG. 26. FIG. 26 shows SPNpositions of entry points with respect to the AV stream file. Arrowsshown in the second row of FIG. 26 indicate the SPN positions of theentry points having PID of 0x1011. EP_ID of each of these entry pointsis a multiple of four, and the I-pictures indicated by these entrypoints are untransformable. Arrows shown in the third row of FIG. 26indicate SPN positions where beginnings of the I-pictures of thesecondary video having PID of 0x1B00 exist. Here, with respect to eachSPN position whose PID is 0x1011 and EP_ID is a multiple of four, anI-picture, of the secondary video having PID of 0x1B00, whose SPN at thebeginning thereof is closest to the SPN position is rendereduntransformable.

For example, in FIG. 26, among the I-pictures having PID of 0x1B00, theI-picture#B is the beginning of the picture closest to the SPN indicatedby the entry point whose PID is 0x1011 and EP_ID is 4N. Accordingly,this I-picture is rendered untransformable. Similarly, among theI-pictures having PID of 0x1B00, the I-picture#c is the beginning of thepicture closest to the SPN of the entry point whose PID is 0x1011 andEP_ID is 4(N+1). Accordingly, this I-picture is rendereduntransformable. With this data structure, when performingfast-forward/rewind of primary and secondary videos, the playbackapparatus can easily search and play I-pictures which are close to eachother in terms of file position, thereby realizing efficientfast-forward/rewind of the primary and secondary videos by the playbackapparatus as a result.

It should be noted that this can be modified such that when thedifference between SPN of an entry point whose PID is 0x1011 and EP_IDis a multiple of four, and SPN of, among I-pictures having PID of0x1B00, an I-picture whose SPN is closest to the SPN pertaining to PIDof 0x1011 is more than the size determined by (the maximum temporalinterval between I-pictures set by the format)*(bitrate size of theAVclip), the I-picture pertaining to PID of 0x1B00 does not need to berendered untransformable. As a result, when playing an I-picture of theentry point whose PID is 0x1011 and EP_ID is a multiple of four, theplayback apparatus is not required to play back a part unnecessarilyfurther away to play back an untransformable I-picture of an entry pointhaving PID of 0x1B00, thereby reducing the load on the playbackapparatus.

(5) As another modification, the untransformable I-pictures in thesecondary video may be determined as shown in FIG. 27.

FIG. 27 shows PTS positions of entry points with respect to the STCwhich is the playback time axis of the AV stream. Arrows shown in thesecond row of FIG. 27 indicate the PTS positions of the entry pointshaving PID of 0x1011. EP_ID of each of these entry points is a multipleof four, and the I-pictures indicated by these entry points areuntransformable. Arrows shown in the third row of FIG. 27 indicate thePTS positions of the entry points having PID of 0x1B00. Here, withrespect to each PTS position whose PID is 0x1011 and EP_ID is a multipleof four, part of the stream from SPN of, among the entry points whosePID is 0x1B00 and whose PTS is equivalent to or positioned anterior tothe PTS position, an entry point whose PTS is closest to the PTSposition, to SPN of the next entry point having PID of 0x1B00 isrendered untransformable.

For example, among the entry points whose PID is 0x1B00 and PTS isequivalent to or positioned anterior to PTS of the entry point whose PIDis 0x1011 and EP_ID is 4N, the entry point having EP_ID of A is closestto the PTS of the entry point whose PID is 0x1011 and EP_ID is 4N. Andthe next entry point having PID of 0x1B00 is the entry point havingEP_ID of B. Accordingly, the secondary video stream between SPNs ofthese two entry points is rendered untransformable. Similarly, among theentry points whose PID is 0x1B00 and whose PTS is equivalent to orpositioned anterior to PTS of the entry point whose PID is 0x1011 andEP_ID is 4(N+1), the entry point having EP_ID of C is closest to the PTSof the entry point whose PID is 0x1011 and EP_ID is 4(N+1). And the nextentry point having PID of 0x1B00 is the entry point having EP_ID of D.Accordingly, the secondary video stream between SPNs of these two entrypoints is rendered untransformable.

With this data structure, when performing fast-forward/rewind of primaryand secondary videos, the playback apparatus can easily search thesecondary video stream which has the same PTS as the presentation time,thereby realizing efficient fast-forward/rewind of the primary andsecondary videos by the playback apparatus as a result.

(6) As another modification, the untransformable I-pictures in thesecondary video may be determined as shown in FIG. 28.

FIG. 28 shows PTS positions of entry points with respect to the STCwhich is the playback time axis of the AV stream. The arrows shown inthe second row of FIG. 28 indicate the PTS positions of the entry pointshaving PID of 0x1011. EP_ID of each of these entry points is a multipleof four, and the I-pictures indicated by these entry points areuntransformable. Arrows shown in the third row of FIG. 28 indicate thePTS positions of the entry points having PID of 0x1B00. Here, withrespect to each PTS position whose PID is 0x1011 and whose EP_ID is amultiple of four, part of the stream from SPN of, among the entry pointswhose PID is 0x1B00 and whose PTSs are positioned anterior to the PTSposition, an entry point whose PTS is closest to the PTS position, toSPN of the next entry point having PID of 0x1B00 is rendereduntransformable. However, it should be noted, with respect to each PTSposition whose PID is 0x1011 and whose EP_ID is a multiple of four, ifan entry point whose PID is 0x1B00 and whose PTS is equivalent to thePTS position exists, an I-picture indicated by this entry point isrendered untransformable.

For example, among the entry points whose PID is 0x1B00 and whose PTSsare positioned anterior to PTS of the entry point whose PID is 0x1011and EP_ID is 4N, the entry point having EP_ID of A is closest to the PTSof the entry point whose PID is 0x1011 and EP_ID is 4N. And the nextentry point having PID of 0x1B00 is the entry point having EP_ID of B.Accordingly, the secondary video stream between SPNs of these two entrypoints is rendered untransformable. Further, among the entry pointswhose PID is 0x1B00, PTS of the entry point having EP_ID of C isequivalent to the PTS of the entry point whose PID is 0x1011 and EP_IDis 4(N+1). Accordingly, the I-picture indicated by this entry point isrendered untransformable.

With this data structure, when performing fast-forward/rewind of primaryand secondary videos, the playback apparatus can easily search thesecondary video stream which has the same PTS as the presentation time,thereby realizing efficient fast-forward/rewind of the primary andsecondary videos by the playback apparatus as a result.

(7) As another modification, the untransformable I-pictures in thesecondary video may be determined as shown in FIG. 29.

FIG. 29 shows PTS positions of entry points with respect to the STCwhich is the playback time axis of the AV stream. Arrows shown in thesecond row of FIG. 29 indicate the PTS positions of the entry pointshaving PID of 0x1011. EP_ID of each of these entry points is a multipleof four, and the I-pictures indicated by these entry points areuntransformable. Arrows shown in the third row of FIG. 29 indicate thePTS positions of the entry points having PID of 0x1B00. Here, withrespect to each PTS position whose PID is 0x1011 and EP_ID is a multipleof four, part of the stream from SPN of, among the entry points whosePID is 0x1B00 and PTSs are equivalent to or positioned anterior to thePTS position, an entry point whose PTS is closest to the PTS position,to the I-picture of the next entry point having PID of 0x1B00 isrendered untransformable.

For example, among the entry points whose PID is 0x1B00 and PTSs areequivalent to or positioned anterior to PTS of the entry point whose PIDis 0x1011 and EP_ID is 4N, the entry point having EP_ID of A is closestto the PTS of the entry point whose PID is 0x1011 and EP_ID is 4N. Andthe I-picture indicated by the next entry point having PID of 0x1B00 isthe entry point having EP_ID of B. Accordingly, the secondary videostream from SPN of this entry point having EP_ID of A to the I-pictureindicated by the entry point having EP_ID of B is rendereduntransformable. Similarly, among the entry points whose PID is 0x1B00and whose PTSs are equivalent to or positioned anterior to PTS of theentry point whose PID is 0x1011 and EP_ID is 4(N+1), the entry pointhaving EP_ID of C is closest to the PTS of the entry point whose PID is0x1011 and EP_ID is 4(N+1). And the next entry point having PID of0x1B00 is the entry point having EP_ID of D. Accordingly, the secondaryvideo stream from SPN of this entry point having EP_ID of C to theI-picture indicated by the entry point having EP_ID of D is rendereduntransformable.

With this data structure, when performing fast-forward/rewind of primaryand secondary videos, the playback apparatus can easily search thepicture of the secondary video stream which has the same PTS as thepresentation time of the primary video, while at the same time beingable to easily search the I-picture of the secondary video being closestto the presentation time of the primary video, thereby realizingefficient fast-forward/rewind of the primary and secondary videos by theplayback apparatus as a result.

(8) As another modification, the untransformable I-pictures in thesecondary video may be determined as shown in FIG. 30.

FIG. 30 shows PTS positions of entry points with respect to the STCwhich is the playback time axis of the AV stream. Arrows shown in thesecond row of FIG. 30 indicate the PTS positions of the entry pointshaving PID of 0x1011. EP_ID of each of these entry points is a multipleof four, and the I-pictures indicated by these entry points areuntransformable. Arrows shown in the third row of FIG. 30 indicate thePTS positions of the entry points having PID of 0x1B00. Here, withrespect to each PTS position whose PID is 0x1011 and EP_ID is a multipleof four, part of the stream from SPN of, among the entry points whosePID is 0x1B00 and whose PTS is positioned anterior to the PTS position,an entry point whose PTS is closest to the PTS position, to theI-picture indicated by the next entry point having PID of 0x1B00 isrendered untransformable. However, it should be noted, with respect toeach PTS position whose PID is 0x1011 and EP_ID is a multiple of four,if an entry point whose PID is 0x1B00 and PTS is equivalent to the PTSposition exists, an I-picture, in the secondary video, indicated by thisentry point is rendered untransformable.

For example, among the entry points whose PID is 0x1B00 and whose PTSsare positioned equivalent to or anterior to PTS of the entry point whosePID is 0x1011 and EP_ID is 4N, the entry point having EP_ID of A isclosest to the PTS of the entry point whose PID is 0x1011 and EP_ID is4N. And the next entry point having PID of 0x1B00 is the entry pointhaving EP_ID of B. Accordingly, the secondary video stream from SPN ofthis entry point having EP_ID of A to the I-picture indicated by theentry point having EP_ID of B is rendered untransformable. Further,among the entry points whose PID is 0x1B00, PTS of the entry pointhaving EP_ID of C is equivalent to the PTS of the entry point whose PIDis 0x1011 and EP_ID is 4(N+1). Accordingly, the I-picture indicated bythis entry point is rendered untransformable.

With this data structure, when performing fast-forward/rewind of primaryand secondary videos, the playback apparatus can easily search thepicture of the secondary video stream which has the same PTS as thepresentation time of the primary video, while at the same time beingable to easily search the I-picture of the secondary video being closestto the presentation time of the primary video, thereby realizingefficient fast-forward/rewind of the primary and secondary videos by theplayback apparatus as a result.

It should be noted that when the pictures to be rendereduntransformable, indicated by the entry points of the entry maps of theprimary and secondary videos, are of a field structure and the pictureof the second field is inter-frame encoded (for example, Predictivemethod), both the first and second fields can be rendereduntransformable. With this structure, when executing special playbackwithout restoring the stream, the playback apparatus is able to playback data in both of the first and second fields of the picture, whichare to be rendered untransformable, indicated by the entry map.

Second Embodiment

In the second embodiment, the playback apparatus of the presentinvention is described.

FIG. 31 shows a structure of a playback apparatus 200. The playbackapparatus 200 includes a BD-ROM drive 11, a read buffer 12, a systemtarget decoder 13, a data restoration processing unit 14, a restorationentry generation unit 15, a restoration byte code data execution unit16, a data analysis execution unit 17, and a user event processing unit18.

The BD-ROM drive 11 reads data from the BD-ROM disc based on commandsfrom the data analysis execution unit 17 and stores the read data intothe read buffer 12. The data read from the BD-ROM disc includes theIndex File, Movie Object file, and PlayList file in addition to the AVstream. When a command to read restoration byte code data is generatedby the restoration byte code data execution unit 16, the BD-ROM drive 11reads the restoration byte code data from the BD-ROM disc and transmitsit to the restoration byte code data execution unit 16.

The read buffer 12 is a buffer composed of a memory or the liketemporarily storing the data read using the BD-ROM driver.

The system target decoder 13 performs demultiplexing processing onsource packets read by the read buffer 12, and decodes and plays backeach stream. When data of PMT is transferred from the read buffer 12 anda system target decoder in the system target decoder 13 detects arestoration descriptor, the system target decoder 13 transfers to therestoration entry generation unit 15 the restoration descriptor and SPNof the PMT packet in which the restoration descriptor is described.Details of the system target decoder 13 are described later.

The user event processing unit 18 responds to user operations via theremote controller and requests the data analysis execution unit 13 toexecute processing. For example, when a button on the remote controlleris pressed, the user event processing unit 18 requests the data analysisexecution unit 13 to execute the command contained in the button. Forexample, when the fast-forward/rewind button on the remote controller ispressed, the user event processing unit 18 instructs the data analysisexecution unit 13 to execute fast-forward/rewind processing on the AVstream of the PlayList currently being played back.

The restoration byte code data execution unit 16, upon receiving anexecution command from the data analysis execution unit 17, receives thenumber of the AV stream and the restoration segment ID from the dataanalysis execution unit 17, acquires the restoration byte code data 16from the BD-ROM drive 11, and executes processing. A restorationparameter generated from the restoration byte code data is passed on tothe restoration entry generation unit.

The restoration entry generation unit 15 generates a restoration entryby executing, on the mask restoration entry included in the restorationdescriptor transferred from the system target decoder 13, XOR operationprocessing of the restoration parameter transferred from the restorationbyte code data execution unit 16. The restoration entry generation unit15 transfers SPN of a PMT packet corresponding to the generatedrestoration entry, to the data restoration processing unit 14.

The data restoration processing unit 14 receives the SPN of the PMTpacket corresponding to the restoration entry transferred from therestoration entry generation unit 15 and executes restorationprocessing. When the transformation instruction flag of the restorationentry is “restoration not required”, the data restoration processingunit 14 ignores the restoration entry and performs no processing. Whenthe transformation instruction flag of the restoration entry is“restoration required”, the data restoration processing unit 14identifies a source packet, which is the restoration target, based onthe relative packet count and the SPN of the PMT packet, and finds theidentified source packet in the read buffer 12. The data restorationprocessing unit 14 identifies an overwrite position in the source packetbased on the intra-packet position of the restoration entry, andoverwrites it with the overwrite value.

The data analysis execution unit 17 includes a command processorexecuting navigation commands which constitute a Movie Object, and aplayback control engine. The playback control engine plays back the AVstream, via the PlayList information, based on an execution result ofPlayPL command by the command processor, API calls by a platform unit,and the like. The data analysis execution unit 17 manages how far the AVstream has been played back, and prior to changing of the restorationsegment in the AV stream, instructs the restoration byte code dataexecution unit 16 to execute the restoration byte code data to generatethe next restoration parameter.

The data analysis execution unit 17, upon being notified, by therestoration byte code data execution unit 16, of an execution command ofspecial playback which is high-speed fast-forward/rewind, analyzes theentry map in which PID in the stream information file of the AV streamto be played back indicates the primary video, and identifies entrypoints whose EP_ID is a multiple of four. Next, the data analysisexecution unit 17 analyzes the entry map in which PID in the streaminformation file of the AV stream to be played back indicates thesecondary video. After selecting the entry point of the primary video tobe played back first, the data analysis execution unit 17 selects, inthe entry map of the secondary video, an entry point whose PTS is closeto the PTS of the entry point of the primary video. Following that, thedata analysis execution unit 17 realizes high-speed fast-forward/rewindby repeating the following processing (1) to (4). (1) The data analysisexecution unit 17 notifies the BD-ROM drive 11 of the smallest SPN amongthe selected entry points of the primary video and secondary video, andrequests the BD-ROM drive 11 to start reading from the notified SPN. (2)The data analysis execution unit 17 provides information on the entrypoints of the primary video and secondary video to the system targetdecoder 13, and instructs the system target decoder 13 to play back onlyI-pictures therein. (3) The data analysis execution unit 17 receivesnotification of playback completion of the I-pictures of the primaryvideo and secondary video from the system target decoder 13. (4) Thedata analysis execution unit 17 selects, in the entry map of the primaryvideo, an entry point to be played back next whose EP_ID is a multipleof four, and selects, in the entry map of the secondary video, an entrypoint whose PTS is closest to the PTS of the selected entry point of theprimary video. Note that obviously, not all of the entry points in theprimary video with a multiple of four need to be played back, and theentry points are selected and played back in accordance with the speedof fast-forward/rewind specified by the user.

<System Target Decoder 13>

Next, the system target decoder 13 is described with reference to FIG.32.

A source packetizer 21 interprets source packets transferred to thesystem target decoder 13, fetches TS packets therefrom, and transmitsthe fetched TS packets to a PID filter 23. When transmitting the TSpackets to the PID filter 23, the source packetizer 21 adjusts inputtime to the decoder according to ATS of each source packet.Specifically, when the value of ATC generated by an ATC counter 22coincides with the value of ATC of the source packet, the sourcepacketizer 21 sends only the TS packet to the PID filter 23 inaccordance with the recording rate of the ACVlip.

The PID filter 23 transfers, among the TS packets output from the sourcepacketizer 21, TS packets whose PID coincides with PID required for theplayback to, in accordance with PID, a primary video decoder 24, asecondary video decoder 25, an IG decoder 26, a PG decoder 27, an audiodecoder 28, and a system packet decoder 29. For example, for a BD-ROM,the PID filter 23 sends a TS packet to the primary video decoder 24 whenPID included in the TS packet is 0x1011, to the secondary video decoder25 when PID is 0x1B00 to 0x1B1F, to the audio decoder 28 when PID is0x1100 to 0x111F, to the PG decoder 27 when PID is 0x1200 to 0x121F, tothe IG decoder 26 when PID is 0x1400 to 0x141F, and to the system packetdecoder 29 when PID is 0x0000 indicating PAT or 0x0100 indicating PMT.

The primary video decoder 24 includes TB (TransportStreamBuffer) 30, MB(Multiplexing Buffer) 31, EB (ElementaryStreamBuffer) 32, a compressedvideo decoder 33, RB (Re-order Buffer) 34, and a switch 35.

The TB 30 is a buffer temporarily storing TS packets belonging to avideo stream when the TS packets are output from the PID filter 23.

The MB 31 is a buffer temporarily storing PES packets when the TB 30outputs the video stream to the EB 32.

The EB 32 is a buffer storing encoded pictures (I-pictures, B-pictures,and P-pictures).

The compressed video decoder 33 creates multiple frame images bydecoding each frame image in the video elementary stream according to apredetermined decoding time (DTS). Compression encoding methods used forvideo streams multiplexed into an AV stream include MPEG2, MPEG4AVC,VC1, and the like, and the compressed video decoder 33 is set accordingto the attribute of the stream. The compressed video decoder 33, wheninformation on the entry maps has been transmitted from the dataanalysis execution unit 17 to the system target decoder 13 and theinformation instructs only playback of I-pictures, notifies the dataanalysis execution unit 17 upon completion of decoding of theI-pictures.

The RB 34 is a buffer for changing the order of the decoded picturesfrom the order of encoding to the order of presentation.

The switch 35 is a switch for changing the order of the decoded picturesfrom the order of encoding to the order of presentation. Changeover ofthe switch 35 causes the pictures to be written into a plain memory 42in accordance with the presentation time (PTS).

The secondary video decoder 25 which has the same structure as theprimary video decoder 24 decodes input secondary video streams andwrites the pictures into a plain memory 43 in accordance with thepresentation time (PTS).

The IG decoder 26 extracts and decodes interactive graphics streams fromthe TS packets input from the source packetizer and writes uncompressedgraphics data into a plain memory 44 in accordance with the presentationtime (PTS).

The PG decoder 27 extracts and decodes presentation graphics streamsfrom the TS packets input from the source packetizer and writesuncompressed graphics data into a plain memory 45 in accordance withtheir presentation time (PTS).

The addition unit 46 instantaneously overlaps the data written in theplain memories 42, 43, 44, and 45 and displays the overlapped data on TVor the like.

The audio decoder 28 is composed of TB (TransportStreamBuffer) 36, B(Buffer) 37, and a compressed audio decoder 38.

The TB 36 stores the TS packets output from the PID filter 23 in afirst-in first-out manner and transfers the stored TS packets to the B37 at a constant bitrate.

The B 37 stores the audio stream input from the TB 36 in a first-infirst-out manner and provides the stored audio stream to the compressedaudio decoder 38 in units of PES packets.

The compressed audio decoder 38 performs decoding processing on theinput PES packets, thereby obtaining audio data in compressed LPCM, andoutputs the obtained audio data in accordance with the playback time(PTS). Compression encoding methods for audio streams to be multiplexedinto an AV stream include AC3, DTS and the like. The compression videodecoder 33 is switched in accordance with the attribute of the stream.

The system packet decoder 29 is composed of TB (TransportStreamBuffer)39, B (Buffer) 40, and a system packet analysis unit 41.

The TB 39 stores the TS packets output from the PID filter 23 in afirst-in first-out manner and transfers the stored TS packets to the B40 at a constant bitrate.

The B 40 transfers the data input from the TB 39 at a constant transferrate and data of PAT and PMT, to the system packet analysis unit 41.

The system packet analysis unit 41 analyzes contents of inputtransferred PAT and PMT. For example, the system packet analysis unit 41analyzes stream information described in PMT and initializes therespective decoders. When PMT includes a restoration descriptor at thebeginning thereof, the system packet analysis unit 41 extracts therestoration descriptor and notifies the restoration entry generationunit 15 of SPN of the PMT packet.

Described above is the hardware structure of the playback apparatus ofthe present invention.

Next, detailed description is given on operations during high-speedfast-forward/rewind playback, which is the feature of the playbackapparatus of the present embodiment. The operations during high-speedfast-forward/rewind playback are controlled by the data analysisexecution unit 17. FIG. 33 is a flowchart showing the processing by thedata analysis execution unit 17.

Upon receiving a fast-forward/rewind instruction by user operation, thedata analysis execution unit 17 first sets a variable n allocated on awork memory to 0 (S101), and determines a multiple-speed parameter A inaccordance with the specified playback speed (S102).

After that, the data analysis execution unit 17 selects entry points ofthe primary video and secondary video for playback by executing playbackentry point selection processing using the variable n and multiple-speedparameter A (S103) and instructs the system target decoder 13 to playback the I-pictures indicated by the selected entry points (S104).

The data analysis execution unit 17 executes the above-mentionedprocessing repeatedly (S103 to S105), and upon receiving a stopinstruction by the user or reaching the end of the entry map (S105: No),ends the special playback.

Next, description is given on the playback entry point selectionprocessing. FIG. 34 is a flowchart showing processing steps of theplayback entry point selection processing.

In the playback entry point selection processing, the data analysisexecution unit 17 first searches the entry map of the primary video forthe 4An-th entry point, and selects the entry point as the playbacktarget of the primary video (S111).

Next, the data analysis execution unit 17 searches the entry map of thesecondary video for an entry point whose PTS is closest to PTS of theentry point of the primary video selected in S111 (S112). Here, when twoentry points are detected in the secondary video (S113: Yes), one of thetwo which is posteriorly positioned to the other in terms of time isselected as the playback target of the secondary video (S114). When oneentry point is detected in the secondary video in S112 (S113: No), thedetected entry point is selected as the playback target of the secondaryvideo (S115). Lastly, the data analysis execution unit 17 increments thevariable n by one (S116) and after that, performs the high-speedfast-forward/rewind playback shown in FIG. 33.

Up to this point, the playback entry point selection processing has beendescribed in detail.

As described above, according to the present embodiment, when an AVstream is read, for performing high-speed fast-forward/rewind playbackthereof, from a recording medium on which copyright protection at the TSpacket level has been realized by recording the AV stream which ispartially transformed, an increase in the processing load can be avoidedby selectively using the following TS packets: TS packets which areensured to be untransformed, that is, TS packets constituting everyfourth entry unit in the primary video stream and TS packetsconstituting entry units in the secondary video stream, each of whichhas a presentation time stamp closest to anyone of the every fourthentry unit in the primary video stream.

Third Embodiment

In the third embodiment, an embodiment of the recording apparatus andrecording method of the present invention is described. For theproduction and manufacturing of the BD-ROM mentioned in the firstembodiment, the recording apparatus and the recording method of thepresent invention are used.

Here, the recording apparatus is so-called an authoring apparatus whichis installed at production studios for distributing motion picturecontent and used by authoring staff. A use form of the recordingapparatus of the present invention is as follows: the recordingapparatus generates digital streams which are compression encoded inaccordance with MPEG standard and scenarios which describe how to playback motion picture Titles, and generates, for BD-ROM, a volume imageincluding these. The object of the recording apparatus of the presentinvention is to generate the recording medium described in the firstembodiment.

FIG. 35 shows the internal structure of the recording apparatus of thepresent invention. As shown in the figure, the recording apparatus ofthe present invention includes a material production unit 201, ascenario generation unit 202, a multiplexing unit 203, a restorationentry generation unit 204, a restoration byte code data generation unit205, a transformation processing unit 206, a format processing unit 207,and a master production unit 208.

The material production 201 creates streams such as video streams, audiostreams, presentation graphics streams, and interactive graphicsstreams. The material production unit 201 creates video streams byencoding video images such as uncompressed bit map in accordance with acompression standard such as MPEG4-AVC and MPEG2. Also, the materialproduction unit 201 creates audio streams by encoding uncompressedLinear PCM audio and the like in accordance with a compression standardsuch as AC3. The material production unit 201 creates presentationgraphics streams which are formats of subtitle streams conforming to theBD-ROM standard, based on a subtitle information file which includessubtitle images, presentation timing, and subtitle effects such asfade-in/fade-out. The material production unit 201 creates interactivegraphics streams which are formats of menu screens conforming to theBD-ROM standard, based on bitmap images used for the menu and a menufile describing transition of buttons on the menu and presentationeffects.

The scenario generation unit 202 creates scenarios in a formatconforming to the BD-ROM standard in accordance with information on thestreams created by the material production unit 201 and operations bythe authoring staff via GUI. Here, the scenarios correspond to filessuch as the Index File, Movie Object file, and PlayList file. Thescenario generation unit 202 further creates parameter files eachdescribing which streams compose which AV stream, to realizemultiplexing processing.

The multiplexing unit 203 multiplexes multiple streams such as video,audio, subtitles, buttons and the like described in BD-ROM scenario datainto an AV stream in MPEG2-TS format. Here, a stream information filecorresponding one-to-one with the AV stream is created as well. Creationof the stream information file by the multiplexing unit 203 is performedas follows. The multiplexing unit 203 creates entry maps while creatingthe AV stream. More specifically, the multiplexing unit 203, in each ofthe streams generated by the material production unit 201, detects whereI-pictures exist if the contained video stream is MPEG2, whereI-pictures or IDR pictures exist if the contained video stream isMPEG4-AVC, and where I-pictures exist if the contained video stream isVC-1. The multiplexing unit 203 then registers, in the entry map, entrypoints each of which associates the presentation time of the picturewith a source packet, in the AV stream in the MPEG2-TS format, in whichthe starting data of the pictures exists. When there are two kinds ofvideo streams, that is, a primary video stream and a secondary videostream in the AV stream, the multiplexing unit 203 creates entry mapsfor these two simultaneously. The multiplexing unit 203 creates thestream information file in which the entry maps created therebycorrespond one-to-one with attribute information indicating audioattribute, video attribute and the like for each of the streams includedin the AV stream. Also, the multiplexing unit 203 creates, withoutcausing overflow to the buffer in the system target decoder 2409, alarge number such as 50 pieces, per second, of PMT packets. In theBD-ROM, a restoration entry for transforming an AV stream needs to beinserted as a restoration descriptor into a PMT packet in the AV stream.Thus, a large number of PMT packets are required to realize a largeamount of data transformation in the AV stream.

The restoration entry generation unit 204 analyzes contents of the AVstream, selects pre-transformation data to be transformed, and createsrestoration entries. The restoration entry generation unit 204 selectsthe pre-transformation data effectively such that the image is distortedand the AV stream cannot be played back properly when an unauthorizedplayback apparatus plays back the AV stream without restoration. Here, alarge playback distortion due to transforming pre-transformation data isdefined as “a large transformation effect”. In order to selectpre-transformation data enabling a large transformation effect when theAV stream contains a video stream, the following priorities are takeninto account. (1) Pre-transformation data is selected in the followingorder of priority: IDR-picture/I-picture->P-picture->B-picture. (Since acompression method of a video stream uses compression based on temporalcorrelation, transforming a picture which largely affects correlation ofpictures increases the transformation effect.) (2) A slice header and aperiphery around the beginning of slice data in the picture are selectedas pre-transformation data. (A video stream can be decoded in units ofslices, and because slice headers and the beginning of slice data arethe most important data for the decoder, transformation of these or avicinity thereof increases the transformation effect.) (3) When thereare multiple slices in the picture, the first slice is given higherpriority when selecting pre-transformation data. (The first slice headerincludes such as a parameter common to slices in the picture, and thus,transforming the first slice header increases the transformationeffect.) With respect to the pre-transformation data selected as above,SPN of PMT positioned anterior thereto is found out and thetransformation instruction flag, relative packet, intra-packet position,and overwrite value are set, thereby creating a restoration entry. Also,the restoration byte code data generation unit 205 refers to the entrymap in the stream information file, and avoids selectingpre-transformation data from the I-pictures, in the entry map of theprimary video, whose EP_ID is a multiple of four, for the primary videostream. In addition, the restoration byte code data generation unit 205refers to the stream information file in the entry map, and avoidsselecting pre-transformation data from an I-picture indicated by anentry point, in the entry map of the secondary video, whose PTS isclosest to that of the entry point whose EP_ID is a multiple of four.

The restoration byte code data generation unit 205 calculatesrestoration segments based on the AV stream and the stream informationfile, and creates restoration parameters corresponding one-to-one withthe restoration segments. Also, the restoration byte code datageneration unit 205 generates restoration byte code data with respect tothe AV stream number and restoration segment ID so as to be able togenerate restoration parameter. When generating the restoration bytecode data, some efforts may be made. These efforts are, for example,with use of a key on the BD-ROM disc or in the playback apparatus,allowing only the playback apparatus having the correct key to generatethe restoration parameter, thereby preventing an illegal playbackapparatus from performing playback, or obfuscating program codes toprevent the program itself from being illegally analyzed. Additionally,for the restoration byte code data, the restoration byte code datageneration unit 205 creates a mask restoration entry obtained byperforming XOR on the restoration entry using the restoration parameter,and creates a restoration entry packet in which a base SPN indicatingthe pre-transformation data indicated by the restoration entry is set,and includes these in the restoration byte code data.

The transformation processing unit 206 performs transformationprocessing on the AV stream based on the restoration entries created bythe restoration entry generation unit and the restoration parametersgenerated by the restoration byte code data generation unit 205, therebycreating a transformed AV stream. The restoration byte code datageneration unit 205 creates a mask restoration entry by performing XORon the restoration entry using the restoration parameter, converts themask restoration entry to the restoration descriptor, and inserts theconverted restoration descriptor into PMT positioned immediately beforethe pre-transformation data indicated by the restoration entry.Following that, the transformation processing unit 206 overwrites theposition of the pre-transformation data indicated by the restorationentry with a data string such as a random value. When nopre-transformation data exists between the PMT and the next PMT, thetransformation processing unit 206 creates anew restoration entry, setsthe restoration instruction flag to “transformation not required”,generates a mask restoration entry by performing XOR on the restorationentry with the restoration parameter, generates a restorationdescriptor, and inserts the generated restoration descriptor into thePMT.

The format processing unit 207 arranges the following into files anddirectories conforming to the BD-ROM standard, thereby generating a discimage in the UDF format which is a file system conforming to the BD-ROMstandard: the BD-ROM scenario data generated by the scenario generationunit 202, the transformed AV stream generated by the transformationprocessing unit 206, the stream information file generated by themultiplexing unit 203, and the restoration byte code data generated bythe restoration byte code data generation unit 205.

The master production unit 208 creates data for BD-ROM pressing from thedisc image generated by the format processing unit 207. A BD-ROM can bemanufactured by performing pressing processing on this data.

Described above is the structure of the recording apparatus.

In the following, the BD-ROM recording method of the recording apparatusis described with reference to FIG. 36.

In a step S201, the material production unit 201 generates the videostreams, audio streams, IG streams, and PG streams. In a step S202, thescenario generation unit 202 creates the BD-ROM scenario data describingplayback scenario, such as the IndexFile, Movie Object file, andPlayList file. In a step S203, the multiplexing unit 203 creates the AVstream and stream information file based on the BD-ROM scenario data.

Here, the restoration entry generation unit 204 executes untransformablepacket specification processing, thereby specifying untransformablepackets which are not allowed to be transformed, among the TS packets inthe primary video and secondary video (S204). After that, therestoration entry generation unit 204 selects pre-transformation datafrom among TS packets which are other than the untransformable packetsspecified in the step S204, and creates a restoration entry (S205).

The restoration byte code data generation unit 205 generates restorationbyte code data which outputs the restoration parameter used to generatethe restoration entry in the step S205 (S206), and the transformationprocessing unit 206 creates a transformed AV stream based on therestoration entry and the AV stream (S207).

Lastly, the format processing unit 207 rearranges the BD-ROM scenariodata, transformed AV stream, stream information file, and restorationbyte code data into a file-directory structure conforming to the BD-ROMstandard, thereby creating a disc image conforming to the BD-ROMstandard (S208), and the master generation unit 208 creates the data forBD-ROM pressing (S209). These are the processing steps of the BD-ROMrecording processing by the recording apparatus of the presentembodiment.

Next, the untransformable packet specification processing is describedin detail. FIG. 37 is a flowchart showing processing steps of theuntransformable packet specification processing.

In the untransformable packet specification processing, the restorationentry generation unit 204 first sets the variable m allocated on thework memory to 0 (S211):

After that, the restoration entry generation unit 204 refers to theentry maps in the stream information file generated by the multiplexingprocessing unit 203 in S203 in FIG. 36, and specifies, among the TSpackets constituting the AV stream, TS packets constituting an I-pictureindicated by the entry point whose EP_ID is 4m in the entry map of theprimary video, as the untransformable packets (S212). Furthermore, therestoration entry generation unit 204 specifies, as the untransformablepackets, the TS packets constituting an I-picture indicated by an entrypoint, in the entry map of the secondary video, whose PTS is closest tothe entry point, in the entry map of the primary video, whose EP_ID is4m (S213).

Following that, restoration entry generation unit 204 increments thevariable m by one (S214), repeats the processing steps of S212 to S215,thereby adding specification of the untransformable packets, until 4mexceeds the final EP_ID of the entry map of the primary video, and when4m exceeds the final EP_ID of the entry map of the primary video (S215:No), ends the untransformable packet specification processing.

Above is the detail of the untransformable packet specificationprocessing.

As described above, according to the present embodiment, even in a casewhere copyright protection at the TS packet level has been realized bytransforming part of an AV stream and recording the AV stream, TSpackets constituting every fourth entry unit in the primary video streamand TS packets constituting entry units in the secondary video streameach having a presentation time stamp closest to any one of the everyfourth entry unit in the primary video stream are not transformed.Consequently, as a result of selective use of the I-pictures stored inthese TS packets by the playback apparatus, high-speedfast-forward/rewind playback can be performed without restorationprocessing of TS packets.

(Other Modifications)

While the present invention has been described through the embodimentsabove, it is not limited to these embodiments, and, for example,includes the following modifications as well.

(1) The present invention may be a playback/recording method disclosedby the processing steps of the flowchart explained in each embodiment.Also, the present invention may be a computer program including programcodes which operate a computer using the processing steps, and may be adigital signal of the computer program.

Also, the present invention may be a computer-readable recording mediumsuch as a flexible disk, a hard disk, a CD-ROM, an MO, a DVD, a DVD-ROM,a DVD-RAM, a BD (Blu-ray Disc) or a semiconductor memory, that storesthe computer program or the digital signal.

Furthermore, the present invention may be the computer program or thedigital signal transmitted on an electric communication network, awireless or wired communication network, or a network of which theInternet is representative.

Furthermore, by transferring the program or the digital signal to therecording medium, or by transferring the program or the digital signalvia a network or the like, the program or the digital signal may beexecuted by another independent computer system.

(2) The present invention can also be realized by a LSI that controlsthe playback/recording apparatus described the embodiments above. Such aLSI can be achieved by integrating the functional blocks indicated inFIG. 31 of FIG. 35. These functional blocks may be partially or entirelyimplemented by one chip.

Though the LSI is described here, the circuit may be called an IC, asystem LSI, a super LSI, or an ultra LSI, depending on the degree ofintegration.

Also, the integration is not limited to the LSI, and may be performedusing a dedicated circuit or a general processor. A FPGA (FieldProgrammable Gate Array) that can be programmed after LSI manufacturingor a reconfigurable processor capable of reconfiguring connections andsettings of circuit cells in an LSI may be used.

Also, if an integrated circuit technique that replaces a LSI emergesfrom advancement of semiconductor technology or other derivativetechnology, such a technique can be used for the integration of thefunctional blocks and components. For instance, biotechnology may beadapted in this way.

(3) The first to third embodiments describe the structure where theentry points, of the primary video, whose EP_ID is a multiple of fourare ensured to be untransformed at the TS packet level. However,according to the present invention, it is not limited to the entrypoints having EP_ID of a multiple of four which are ensured to beuntransformed at the TS packet level. One TS packet in how many entrypoints is ensured to be untransformed is set appropriately according tothe format characteristics.

(4) While in the first embodiment, as shown in FIG. 18, the restorationentry is recorded on the recording medium after being masked andinserted into PMT as a descriptor, the restoration entry may be recordedon the recording medium using another method.

For example, as shown in FIG. 38, the restoration entry may be insertedinto the restoration byte code data. In this case, while having the samestructures as those in FIG. 18, the restoration entry and the maskrestoration entry are inserted into the restoration byte code data as arestoration entry packet instead of as the restoration descriptor. Therestoration entry packet has a base SPN and the mask restoration entry,and the base SPN stores a value obtained by subtracting the relativepacket count of the restoration entry from SPN where thepre-transformation data exists. The restoration entry packet is storedin the restoration byte code data and is managed for each restorationsegment ID.

(5) In the embodiments above, only part of the BD-ROM standard which isrelated to the present invention is excerpted, and description is givenusing only the representative directories and files. However, obviously,the present invention is able to record other files stipulated in theBD-ROM standard on the BD-ROM.

(6) While in the embodiments above, a BD-ROM conforming to the BD-ROMstandard are used as an example, the features of the present inventiondo not depend on physical characteristics of the BD-ROM, and the presentinvention can be applied to other recording media.

(7) The present invention may be any combination of the above-describedembodiments and modifications.

1. A non-transitory computer-readable recording medium comprising arecording area that has recorded thereon an AV stream and streaminformation, wherein the AV stream includes (a) TS packets composing aprimary video stream and (b) TS packets composing a secondary videostream, the stream information includes: a first entry map indicating aplurality of associations each associating (a) a start position of,among the TS packets composing the primary video stream, a group of TSpackets which constitute an entry unit with (b) a presentation timestamp of the group of TS packets of the primary video stream; and asecond entry map indicating a plurality of associations each associating(a) a start position of, among the TS packets composing the secondaryvideo stream, a group of TS packets which constitute an entry unit with(b) a presentation time stamp of the group of TS packets of thesecondary video stream, each group of TS packets constituting an entryunit stores an intra-frame encoded image therein, among the TS packetscomposing the primary video stream, one or more TS packets have beentransformed by replacement of the TS packets with another piece of dataand TS packets which constitute every N-th entry unit, in an order ofthe start position, are not transformed by the replacement, N being aninteger of 2 or more, each TS packet which constitutes one of the entryunits of the secondary video stream and whose presentation time stamp isin a predetermined relationship with a presentation time stamp of theevery N-th entry unit of the primary video stream, is not transformed bythe replacement, the one or more transformed TS packets are decodableonly after restoration processing, the restoration processing beingperformed for restoring the one or more transformed TS packets to one ormore untransformed packets, and TS packets that have not beentransformed by the replacement are decodable without the restorationprocessing.
 2. The recording medium of claim 1, wherein when thepresentation time stamps with respect to two of the entry units of thesecondary video stream are in the predetermined relationship with thepresentation time stamp of a same one of the every N-th entry unit ofthe primary video stream, TS packets constituting one of the two entryunits that is temporally posterior to the other entry unit areuntransformed.
 3. The recording medium of claim 2, wherein thepredetermined relationship is to be, among the presentation time stampsof the entry units of the secondary video stream, temporally closest tothe presentation time stamp of any one of the every N-th entry unit ofthe primary video stream.
 4. The recording medium of claim 2, whereinthe predetermined relationship is to be, among the presentation timestamps of the entry units of the secondary video stream, temporallyposterior to and closest to the presentation time stamp of any one ofthe every N-th entry unit of the primary video stream.
 5. The recordingmedium of claim 2, wherein the primary video stream and the secondaryvideo stream each include intra-frame encoded images with an interval ofa predetermined value or less between any two adjacent intra-frameencoded images, and the predetermined relationship is to be, among thepresentation time stamps of the entry units of the secondary videostream, temporally posterior to and closest to the presentation timestamp of any one of the every N-th entry unit of the primary videostream, and a difference between the presentation time stamp of the anyone of the every N-th entry unit of the primary video stream and thepresentation time stamp of the entry unit, of the secondary videostream, which is temporally posterior thereto and closest thereto isless than the predetermined value.
 6. The recording medium of claim 1further having recorded thereon a restoration program which outputs arestoration parameter when executed, wherein the AV stream includes amasked table multiplexed therein, and restoration processing forrestoring the transformed TS packets is executed by (a) performing acalculation using the masked table and the restoration parameter, and(b) overwriting the transformed packets with a result of thecalculation.
 7. The recording medium of claim 1, wherein the every N-thentry unit of the primary video stream in the first entry map, and theone of entry units of the secondary video stream and whose presentationtime stamp is in the predetermined relationship with the presentationtime stamp of the every N-th entry unit of the primary video stream areentry units whose intra-frame encoded images stored in TS packets whichconstitutes the entry units are synchronously played back in specialplayback.
 8. A playback apparatus which reads an AV stream and streaminformation from a recording medium and plays back the read AV stream,wherein the AV stream includes (a) TS packets composing a primary videostream and (b) TS packets composing a secondary video stream, and thestream information includes: a first entry map indicating a plurality ofassociations each associating (a) a start position of, among the TSpackets composing the primary video stream, a group of TS packets whichconstitute an entry unit with (b) a presentation time stamp of the groupof TS packets of the primary video stream; and a second entry mapindicating a plurality of associations each associating (a) a startposition of, among the TS packets composing the secondary video stream,a group of TS packets which constitute an entry unit with (b) apresentation time stamp of the group of TS packets of the secondaryvideo stream, each group of TS packets constituting an entry unit storesan intra-frame encoded image therein, the playback apparatus comprises:a reader circuit that reads TS packets included in the AV stream inaccordance with the first entry map and the second entry map; ademultiplexer circuit that demultiplexes the read TS packets into the TSpackets composing the primary video stream and the TS packets composingthe secondary video stream; two video decoders that decode the TSpackets composing the primary video stream and the TS packets composingthe secondary video stream, respectively; a read buffer that buffers TSpackets between the reader circuit and the demultiplexer circuit; arestoration circuit that restores, among TS packets in the read buffer,TS packets which have been transformed by replacement of the TS packetswith another piece of data, among the TS packets composing the primaryvideo stream, one or more TS packets have been transformed by thereplacement and TS packets which constitute every N-th entry unit, in anorder of the start position, are not transformed by the replacement, Nbeing an integer of 2 or more, each TS packet which constitutes one ofthe entry units of the secondary video stream and whose presentationtime stamp is in a predetermined relationship with a presentation timestamp of the every N-th entry unit of the primary video stream, is nottransformed by the replacement, the one or more transformed TS packetsare restored to one or more untransformed TS packets by the restorationcircuit, and the one or more untransformed packets are decodable by thevideo decoders, and TS packets that have not been transformed by thereplacement are decodable by the video decoders without the restorationprocessing.
 9. The playback apparatus of claim 8, wherein when thepresentation time stamps with respect to two of the entry units of thesecondary video stream are, among the presentation time stamps of theentry units of the secondary video stream, temporally closest to thepresentation time stamp of a same one of the every N-th entry unit ofthe primary video stream, TS packets constituting one of the two entryunits that is temporally posterior to the other entry unit areuntransformed.
 10. The playback apparatus of claim 9 further comprisinga playback controller, wherein the playback controller, when instructedto perform a special playback, (i) acquires, from the first entry map,each start position with respect to the every N-th entry unit of theprimary video stream, (ii) further acquires, from the second entry map,each start position of the entry units of the secondary video stream,the presentation time stamp associated with each of which is closest tothe presentation time stamp of a different one of the every N-th entryunit of the primary video stream, (iii) instructs the demultiplexercircuit to separate, from a TS packet at each start position in the readbuffer, TS packets subsequent thereto, and (iv) instructs the two videodecoders to decode part of TS packets separated from the start positionsof the primary video stream and part of TS packets separated from thestart positions of the secondary video stream, each part beingequivalent to one intra-frame encoded image.
 11. The playback apparatusof claim 10, wherein the recording medium has further recorded arestoration program which outputs a restoration parameter when executed,the AV stream includes a masked table multiplexed therein; thedemultiplexer circuit demultiplexes the masked table from the AV stream,the restoration circuit includes: an execution circuit that obtains therestoration parameter by executing the restoration program; and acalculation circuit that obtains a plain table by performing acalculation using the masked table and the restoration parameter, andrestoration processing to restore the transformed TS packets isperformed by overwriting the transformed TS packets in the read bufferusing the plain table.
 12. The playback apparatus of claim 11, whereinthe calculation is an XOR operation.
 13. The playback apparatus of claim8, wherein in special playback, the playback apparatus synchronouslyplays back intra-frame encoded images stored in TS packets whichconstitute the every N-th entry unit of the primary video stream in thefirst entry map, and intra-frame encoded images stored in TS packetswhich constitute the one of entry units of the secondary video streamand whose presentation time stamp is in the predetermined relationshipwith the presentation time stamp of the every N-th entry unit of theprimary video stream.
 14. The playback apparatus of claim 8, whereinafter the restorator restores the one or more transformed TS packetsamong the TS packets composing the primary video stream, the two videodecoders decode the restored TS packets of the primary video stream andTS packets of the secondary video stream whose presentation time stampsare to be synchronous with presentation time stamps of the restored TSpackets.
 15. A recording apparatus comprising: a multiplexer circuitthat obtains a multiplexed stream by multiplexing TS packets composing aprimary video stream and TS packets composing a secondary video stream;a first entry map generator circuit that generates a first entry mapindicating a plurality of associations each associating (a) a startposition of, among the TS packets composing the primary video stream, agroup of TS packets which constitute an entry unit storing therein anintra-frame encoded image with (b) a presentation time stamp of thegroup of TS packets of the primary video stream; a second entry mapgenerator circuit that generates a second entry map indicating aplurality of associations each associating (a) a start position of,among the TS packets composing the secondary video stream, a group of TSpackets which constitute an entry unit storing therein an intra-frameencoded image with (b) a presentation time stamp of the group of TSpackets of the secondary video stream; a specification circuit thatspecifies as untransformable packets, among the TS packets multiplexedin the multiplexed stream,(a) TS packets which constitute every N-thentry unit, in an order of the start position, among the TS packetscomposing the primary video stream, N being an integer of 2 or more, and(b) each TS packet which constitutes one of the entry units of thesecondary video stream and whose presentation time stamp is closest tothe presentation time stamp of the every N-th entry unit of the primaryvideo stream; a transformation circuit that obtains an AV stream by,with use of a restoration parameter, performing a restorabletransformation by replacement of the TS packets with another piece ofdata with respect to some of TS packets among the TS packets in themultiplexed stream other than the untransformable TS packets; a programgenerator circuit that generates a restoration program which outputs therestoration parameter when executed; a recorder circuit that records,onto a recording medium, the AV stream, the first entry map, the secondentry map, and the restoration program, the transformed TS packets aredecodable only after restoration processing, the restoration processingbeing performed for restoring one or more transformed TS packets to oneor more untransformed TS packets, and TS packets that have not beentransformed by the replacement are decodable without the restorationprocessing.
 16. A playback method which reads an AV stream and streaminformation from a recording medium and plays back the read AV stream,wherein the AV stream includes (a) TS packets composing a primary videostream and (b) TS packets composing a secondary video stream, the streaminformation includes: a first entry map indicating a plurality ofassociations each associating (a) a start position of, among the TSpackets composing the primary video stream, a group of TS packets whichconstitute an entry unit with (b) a presentation time stamp of the groupof TS packets of the primary video stream; and a second entry mapindicating a plurality of associations each associating (a) a startposition of, among the TS packets composing the secondary video stream,a group of TS packets which constitute an entry unit with (b) apresentation time stamp of the group of TS packets of the secondaryvideo stream, each group of TS packets constituting an entry unit storesan intra-frame encoded image therein, the playback method comprises:reading TS packets included in the AV stream in accordance with thefirst entry map and the second entry map, and buffering the read TSpackets into a read buffer; restoring, among TS packets in the readbuffer, TS packets which have been transformed by replacement of the TSpackets with another piece of data; demultiplexing, from the readbuffer, the TS packets composing the primary video stream and the TSpackets composing the secondary video stream; and decoding step ofdecoding the TS packets composing the primary video stream and the TSpackets composing the secondary video stream, respectively, among the TSpackets composing the primary video stream, one or more TS packets havebeen transformed by the replacement and TS packets which constituteevery N-th entry unit, in an order of the start position, are nottransformed by the replacement, N being an integer of 2 or more, each TSpacket which constitutes one of the entry units of the secondary videostream and whose presentation time stamp is in a predeterminedrelationship with a presentation time stamp of the every N-th entry unitof the primary video stream, is not transformed by the replacement, thetransformed TS packets are decodable only after restoration processing,the restoration processing being performed for restoring the one or moretransformed TS packets to one or more untransformed TS packets, and TSpackets that have not been transformed by the replacement are decodablewithout the restoration processing.
 17. A recording method for arecording medium, comprising: creating application data; and recordingthe created data onto a recording medium, wherein the application dataincludes an AV stream and stream information, the AV stream includes (a)TS packets composing a primary video stream and (b) TS packets composinga secondary video stream, the stream information includes: a first entrymap indicating a plurality of associations each associating (a) a startposition of, among the TS packets composing the primary video stream, agroup of TS packets which constitute an entry unit with (b) apresentation time stamp of the group of TS packets of the primary videostream; and a second entry map indicating a plurality of associationseach associating (a) a start position of, among the TS packets composingthe secondary video stream, a group of TS packets which constitute anentry unit with (b) a presentation time stamp of the group of TS packetsof the secondary video stream, each group of TS packets constituting anentry unit stores an intra-frame encoded image therein, among the TSpackets composing the primary video stream, one or more TS packets havebeen transformed by replacement of the TS packets with another piece ofdata and TS packets which constitute every N-th entry unit, in an orderof the start position, are not transformed by the replacement, N beingan integer of 2 or more, each TS packet which constitutes one of theentry units of the secondary video stream and whose presentation timestamp is in a predetermined relationship with a presentation time stampof the every N-th entry unit of the primary video stream, is nottransformed by the replacement, the one or more transformed TS packetsare decodable only after restoration processing, the restorationprocessing being performed for restoring the one or more transformed TSpackets to one or more untransformed TS packets, and TS packets thathave not been transformed by the replacement are decodable without therestoration processing.
 18. An integrated circuit of a playbackapparatus which reads an AV stream and stream information from arecording medium and plays back the read AV stream, wherein the AVstream includes (a) TS packets composing a primary video stream and (b)TS packets composing a secondary video stream, the stream informationincludes: a first entry map indicating a plurality of associations eachassociating (a) a start position of, among the TS packets composing theprimary video stream, a group of TS packets which constitute an entryunit with (b) a presentation time stamp of the group of TS packets ofthe primary video stream; and a second entry map indicating a pluralityof associations each associating (a) a start position of, among the TSpackets composing the secondary video stream, a group of TS packetswhich constitute an entry unit with (b) a presentation time stamp of thegroup of TS packets of the secondary video stream, each group of TSpackets constituting an entry unit stores an intra-frame encoded imagetherein, the integrated circuit comprises: a reader circuit that readsTS packets included in the AV stream in accordance with the first entrymap and the second entry map; a demultiplexer circuit that demultiplexesthe read TS packets into the TS packets composing the primary videostream and the TS packets composing the secondary video stream; twovideo decoders that decode the TS packets composing the primary videostream and the TS packets composing the secondary video stream,respectively; a read buffer that buffers TS packets between the readercircuit and the demultiplexer circuit; and a restoration circuit thatrestores, among TS packets in the read buffer, TS packets which havebeen transformed by replacement of the TS packets with another piece ofdata, among the TS packets composing the primary video stream, one ormore TS packets have been transformed by the replacement and TS packetswhich constitute every N-th entry unit, in an order of the startposition, are not transformed by the replacement, N being an integer of2 or more, and each TS packet which constitutes one of the entry unitsof the secondary video stream and whose presentation time stamp is in apredetermined relationship with a presentation time stamp of the everyN-th entry unit of the primary video stream, is not transformed by thereplacement, the one or more transformed TS packets are restored to oneor more untransformed TS packets by the restoration circuit, and the oneor more untransformed packets are decodable by the video decoders, andTS packets that have not been transformed by the replacement aredecodable by the video decoders without the restoration processing. 19.An integrated circuit of a recording apparatus, comprising: Amultiplexer circuit that obtains a multiplexed stream by multiplexing TSpackets composing a primary video stream and TS packets composing asecondary video stream; a first entry map generator circuit thatgenerates a first entry map indicating a plurality of associations eachassociating (a) a start position of, among the TS packets composing theprimary video stream, a group of TS packets which constitute an entryunit storing therein an intra-frame encoded image with (b) apresentation time stamp of the group of TS packets of the primary videostream; a second entry map generator circuit that generates a secondentry map indicating a plurality of associations each associating (a) astart position of, among the TS packets composing the secondary videostream, a group of TS packets which constitute an entry unit storingtherein an intra-frame encoded image with (b) a presentation time stampof the group of TS packets of the secondary video stream; aspecification circuit that specifies as untransformable packets, amongthe TS packets multiplexed in the multiplexed stream, (a) TS packetswhich constitute every N-th entry unit, in an order of the startposition, among the TS packets composing the primary video stream, Nbeing an integer of 2 or more, and (b) each TS packet which constitutesone of the entry units of the secondary video stream and whosepresentation time stamp is closest to the presentation time stamp of theevery N-th entry unit of the primary video stream; a transformationcircuit that obtains an AV stream by, with use of a restorationparameter, performing a restorable transformation by replacing the TSpackets with another piece of data with respect to some of TS packetsamong the TS packets in the multiplexed stream other than theuntransformable TS packets; a program generator circuit that generates arestoration program which outputs the restoration parameter whenexecuted; a recorder circuit that records, onto a recording medium, theAV stream, the first entry map, the second entry map, and therestoration program, the one or more transformed TS packets aredecodable only after restoration processing, the restoration processingbeing performed for restoring the one or more transformed TS packets toone or more untransformed TS packets, and TS packets that have not beentransformed by the replacement are decodable without the restorationprocessing.